Heat exchanger tubes



Oct. 11, 1955 A. HUET 2,720,383

HEAT EXCHANGER TUBES Filed Aug. 20. 1952 INVEflTOR: Hum: HuET' BY ATTORNEY United States Patent HEAT EXCHANGER TUBES Andr Huet, Paris, France Application August 20, 1952, Serial No. 305,424 In France February 24, 1947 Section 1, Public Law 690, August 8, 1946 Patent expires February 24, 1967 2 Claims. (Cl. 257262.12)

The present application is a continuation in part of the patent application Serial Number 11,730, filed February 27, 1948, and now abandoned.

The invention relates to improvements in the manufacture of heat exchange tubes and concerns more particularly tubes according to the applicants earlier Patent No. 2,578,136, which are provided with fins disposed at 180 one from the other and project from the tube in a direction approximately tangential to the external surface of the tube.

When such tubes are disposed in several parallel rows and staggered, and when the fins have their distal ends alined and substantially in contact, there are a number of sinuous fluid or gas lanes between the tubes, with alternately narrowing and widening parts creating variations of speed and pressure in the fluid circulating in them. These variations improve the heat-exchange, as

said in the above cited patent.

According to the present invention, transverse fins or gills are also provided on the tube, in planes perpendicular to the axis of the tube, said fins being waved in an asymmetric manner, in order that the distance between two contiguous fins on the tube be variable, perpendicularly to the direction of the external fluid flowing around the tubes, thereby creating alternately narrow and wide passages, and new variations of speed and pressure in the flow of the external fluid.

The following description, which refers to the accompanying drawings given by way of example, will make clear the manner in which the invention may be carried out.

Fig. 1 is a section of the tube provided with transverse fins or gills.

Fig. 2 is a plan view of a fragment of the tube shown in Fig. 1.

Fig. 3 is a transverse sectional view of a portion of a heat exchanger having tubes provided with tangential fins and arranged in accordance with the present invention.

The tube a is provided with two longitudinal and tangential fins c and d integral with the tube. The fins c and d are located at diametrically spaced points and project in opposite directions tangential to the periphery of the tube and the fin and the fin faces that are remote from the tube axis are lying in parallel planes at opposite sides of the tube axis. The fins c and d are widening progressively from their tips to their roots at the tube surface and they have concave faces nearer the tube axis drawn on arcs merging with the cylindrical surface of the tube.

According to the invention, the tube a is also provided with transverse fins or gills h (Figs. 1 and 2).

When the tubes are assembled in a heat exchanger comprising several rows of tubes, each tube of a row abuts against the neighbouring tubes in the rows at the edges of the fins, to increase the rigidity of the assembly. The fins h have one edge cut to V-shape as at hl while the other edge has a corresponding groove k2. When the tubes are assembled the edges hl engage the recesses h2 of the opposed fins h. Further, the transverse fins h instead of being plain and each situated in a single cross sectional plane of the tube a, are waved as indicated at h3, Fig. 2. The waves of the fins are asymmetric, in order that the distance between two contiguous fins on the same tube, in the direction perpendicular to the fluid which passes, according to the arrows A, around the tube, be variable. Such variable distance creates in the channels between the fins h successively narrow and wide passages, and these variations of section produce variations of speed and pressure in the fluid flowing in the direction of the arrows A. Thereby, the exchange of heat between the external fluid flowing around the tube and the internal fluid traversing the bore: of the tubes at is still increased, in the same manner, as it was, in the perpendicular direction, by the longitudinal fins c and d as aforesaid.

What I claim is:

1. A heat exchanger tube having a body portion of generally cylindrical form disposed transversely of the fluid stream and having a single pair of integral longitudinally extending fins located at diametrically spaced points to project in opposite directions generally tangential to the periphery of the tube with the fin faces that are remote from the tube axis lying in parallel planes at opposite sides of the tube axis; and transverse fins disposed at intervals longitudinally of the tube and extending from the tip of the tangential fin at one side of the tube axis along the curved surface thereof around the tube to the fin at the other side of the tube axis and along the planar portion of said other fin to the tip thereof, said transverse fins being asymmetrically undulated with respect to planes perpendicular to the longitudinal axis of the tube, in order that the distance between two contiguous transverse fins on the tube be variable; said transverse fins each having a V-shaped end adjacent the tip of one tangential fin and a similar V-shaped recess in the end adjacent the other tangential fin.

2. A heat exchanger tube having a body portion of generally cylindrical form disposed transversely of the gas stream and having a single pair of integral longitudinally extending fins located at diametrically spaced points to project in opposite directions generally tangential to the periphery of the tube with the fin faces that are remote from the tube axis lying in parallel planes at opposite sides of the tube axis and the fins widening progressively from their tips to their roots at the tube surface and having concave faces nearer the tube axis drawn on arcs merging with the cylindrical surfaces of the tube so that in transverse section the contour of the tube and the fins have on each side of the tube but one point of change in direction of the curvilinear surface between the tips of the two fins; and transverse fins disposed at intervals longitudinally of the tube and extending from the tip of the tangential fin at one side of the tube axis along the curved surface thereof around the tube to the fin at the other side of the tube axis and along the planar portion of said other fin to the tip thereof; said transverse fins each having a V-shaped end adjacent the tip of one tangential fin and a similar V-shaped recess in the end adjacent the other tangential fin.

References Cited in the file of this patent UNITED STATES PATENTS 1,884,777 Lucke Oct. 25, 1932 1,992,561 Wendel Feb. 26, 1935 FOREIGN PATENTS 397,664 Great Britain Aug. 31, 1933 853,862 France Mar. 30, 1940 1,003,771 France Feb. 24, 1947 

